1. Field of the Invention
The present invention relates to a polarizer protective film, and a polarizer and a liquid crystal display device using the polarizer protective film.
2. Description of the Related Art
With the recent tendency toward advanced upsizing of liquid crystal display devices typically for use for televisions, much desired are high-quality picture technology and price reduction. In future, outdoor-use frequency of display devices typically for digital signage and others is expected to increase more and more, and liquid crystal display devices capable of withstanding use under more extreme weather condition than before are desired.
On the other hand, the polarizer surface on the viewers' side is desired to have various functions of scratch resistance, antireflection, static charge prevention, etc. For making the surface have such functions, generally employed is a method of forming an active energy ray-curable layer on a cellulose acylate film or the like to produce a functional layer-having polarizer-protective film.
The polarizer in a liquid crystal display device that is widely used in the art is so designed that a polarizing element formed by using polyvinyl alcohol (PVA) and iodine is sandwiched between polarizer protective films such as cellulose acylate films, etc. However, the polarizing element formed by using PVA and iodine has a weakness in that the polarizability thereof tends to worsen in high-temperature high-humidity environments; and therefore, the polarizing element of the type must be improved to satisfy the required performance for outdoor use.
For outdoor use, the above-mentioned functional layers are also required to satisfy further severer durability as compared with those for indoor use. Above all, stability to light is an especially important matter; however, ordinary functional layers have a problem in that, when exposed to light for a long period of time, the active energy ray-curable layer therein may be readily peeled from the cellulose acylate film, and improving them is desired.
For improving the lightfastness of resin films, generally employed is a method of adding a UV absorbent or an antioxidant thereto; and for example, Patent Reference 1 discloses a resin film with a triazine-type UV absorbent and a hindered amine-type antioxidant added thereto. Patent Reference 2 discloses a method for forming an active energy ray-curable layer such as a hard coat layer or the like, on a cellulose acylate film containing a hindered amine-type antioxidant.